Scientists seek biocontrols vs. sharpshooters

Help may be on the way from Agricultural Research Service (ARS) scientists in Argentina and Texas for grape growers in California who are battling the glassy winged sharpshooter.

A parasitic wasp could help growers ward off the glassy winged sharpshooters (GWSS) that have been spreading plant-damaging Xylella fastidiosa bacteria in southern California vineyards since the 1990s. Now sharpshooters have made it to Hawaii and Tahiti. ARS scientists in Weslaco, Texas, have shown that the invasive GWSS in California is from Texas — part of the pest's native habitat.

X. fastidiosa causes a variety of costly plant diseases, including Pierce's disease in grapevines and leaf scorch in oleanders. Grape growers in Riverside and San Diego counties have lost about $38 million due to Pierce's disease.

At the ARS South American Biological Control Laboratory in Hurlingham, Argentina, researchers have been evaluating wasps that lay their eggs inside GWSS eggs, which are later consumed by the wasp young as they hatch and feed.

The primary candidate for this form of biological control is currently Gonatocerus tuberculifemur from South America. G. tuberculifemur is being tested, but the wasp has not yet been released.